Windows XP explorer changed behaviour on SP3
Yes, I know, Windows XP is already almost at the end of its life and there isn't much more to add to it. But since I got a new notebook at work to try out and I'm currently in the process of fitting it to my needs, which also involves installing an alternate shell, I'm writing down a small finding for which I found no additional information on the rest of the internet.
The behavior of the "/e" parameter for the Windows Explorer (explorer.exe) has changed between Service Pack 2 and Service Pack 3. This change only has an effect, if there is an alternate Windows shell active. Until SP2 if there is no explorer.exe process running, a call to "explorer.exe /e" starts the shell and tries to open the folder "/e" which obviously leads to an error (and a started Windows shell). If there IS a running "explorer.exe" process found, a call to "explorer.exe /e" opens the file manager window. With SP3 the "/e" is interpreted in a consistent manner and the explorer starts in the File Manager mode regardless if there is already an "explorer.exe" running or not.
So if you're running an alternate shell, want to wire the Windows+E keyboard shortcut to the file manager (or file explorer) using "explorer.exe /e" and experience the Windows Shell starting over your shell with an error, make sure that you install the Service Pack 3 (which you should anyway, regardless of your shell).